1. Field of the Invention
The present invention relates in general to a fluid delivery device, and more particularly, to a fluid delivery device which includes a chemical/electrochemical reagent that expands upon a chemical/electrochemical reaction, such as corrosion, oxidation, reduction, etcetera, thereby generating pressure, and, in turn, delivering a predetermined fluid.
2. Background Art
In many situations it is necessary or desirable to administer relatively small amounts of medicaments, medicines, and/or other pharmaceutical fluids to a patient""s body over a relatively long period of time. For example, heparin is administered to a patient in need thereof by an intravenous xe2x80x9cdripxe2x80x9d procedure. Other medicines which may be administered over long periods of time include antiarrhythmics, streptokinase, vitamins, hormones, and corticosteriods. Other examples of medicines that can benefit from prolonged delivery periods include analgesics, anesthetics, antibiotics, cytostatics, and cytotoxics.
The above-identified medicines can be administered intermittently by bolus injection or continuously by gravity dispensers. Bolus injections may, however, imperfectly match the patient""s actual requirements and subject the patient to larger dosages of drugs than required as well as frequent needle insertion. Continuous drug delivery through gravity dispensers may limit the patient""s lifestyle by tethering him or her to the familiar intravenous drip apparatus. Furthermore, the dispensing rate is not always constant.
Portable units to deliver medicines have been developed that employ mechanical pumps, pressurized gas or the property of an elastic material to return to its original shape. The mechanical pumps use electrical or clockwork motors. The pressurized devices use elastic, inflated balloons or the vapor pressure of a volatile propellant. These devices suffer from many of the drawbacks of the gravity dispensers. Although portable, they generally remain bulky. The mechanical units have numerous moving parts subject to wear and are relatively expensive. They also may have difficulty dispensing small volumes of liquid accurately and precisely.
Gas generating and osmotic devices have been developed that are both portable and somewhat accurate for dispensing small volumes. These gas generating methods include electrolytic cells, Galvanic cells, and oxygen pumps.
An osmotic pump involves imbibing water or another driving fluid. The pump consists of three chambers: a salt chamber, a water chamber, and a drug chamber. The salt and water chambers are separated by a semi-permeable membrane. This membrane is permeable to water but impermeable to salt. The drug chamber is separated from the other two by a flexible diaphragm. Water imbibes osmotically into the salt chamber creating an osmotic pressure which, in turn, exerts a force on the diaphragm thus expelling the drug.
An electrolytic cell comprises a pair of electrodes suspended in an electrolyte. When voltage is applied to the electrodes, the electrolyte gives off a gas which exerts a force on a diaphragm or piston thus expelling the drug.
A Galvanic cell is essentially a metal/electrolyte cell where hydrogen gas is created by reaction of metal with electrolyte thus completing the contact between metal and cathode. The anode and cathode are connected through a resistor. The resistor regulates the current passed through the cell which directly regulates the production of gas.
An oxygen pump transports oxygen from one side of a membrane to the other. Electrodes are placed on opposite surfaces of an electrolytic membrane. Then a voltage gradient is established across the electrolytic membrane. Oxygen is ionized at the first electrode and passes through the membrane where it is reconverted into oxygen at the second electrode. This oxygen can be captured to provide pumping action through the inflation of a bag.
Portable drug delivery systems have been described. For example, U.S. Pat. No. 4,552,561 to Eckenhoff et al. (Nov. 12, 1985) discloses a rigid, tapered housing that is affixed to the wearer by an annular adhesive overlay. Enclosed within the housing is a chamber for the medicament, an imbibing pump, and a traditional needle. One drawback of such a system is that a rigid housing may not easily conform to the contours of the user""s body. Another problem is that the flow rate of an osmotic pump varies with temperature. A change in body or external temperature could have the undesirable effect of changing the medicament flow. In addition, in order to vary the medicament flow, it may be necessary to provide numerous osmotic pumps with differing outputs, or hydrogels with different osmotic properties, or various impermeable membranes to partially preclude the osmotic pump. These limitations make it difficult for the patient to use and control such devices. Osmotic pumps also require charging (the time required for liquid to diffuse through the semi-permeable membrane and begin dissolving the osmagent at steady state) which delays the delivery of the medicament and which limits their suitability for instantaneous or emergency use.
U.S. Pat. No. 4,734,092 to Millerd (Mar. 29, 1988) discloses a flexible housing that is attached to the subject by an adhesive surface incorporated on the housing. Enclosed in the housing is a pump module, a cannula, and a fluid conduit passageway in the form of a spirally wrapped tube. The pump transports atmospheric oxygen into the tube. Such pumping creates a pressure which drives the medicament through the cannula. An oil slug separates the medicament and oxygen. The device is actuated by removing a peel tab and rotating the pump so that the output of the pump aligns with the input of the spiraled tube. The flow can be controlled by varying the current to the pump with a potentiometer. One drawback of such a device is the use of added components for a filtering system of hydrophobic and hydrophilic membranes to keep oil and oxygen from being administered to the patient. Thus, the hydrophobic membrane keeps the medicament in the device while allowing the oxygen to escape. The hydrophilic membrane allows medicament to pass into the body while obstructing oxygen. The hydrophilic membrane is of limited porosity so that it also impedes oil. Another disadvantage of this device is the protrusion of the cannula while in the storage or non-use stage. This exposes the device to possible damage and contamination. Also, a protruding needle does little to re-assure a traumatized or needle-phobic patient. An additional drawback is the difficulty in manufacturing a device with a spiral wrapped tube.
Another development in delivery systems is the transdermal patch. The patch is attached to the skin by an adhesive surface. Medicine then passes through the patch and the skin. A drawback of transdermal drug delivery technology is that certain molecules are very difficult to administer in effective doses. In addition, control of the drug administration can be limited. Moreover, in the case of iontophoretic drug delivery, competing ions can be problematic.
While the above-identified fluid delivery devices have become publicly known, there remains a substantial commercial demand for a simple, economical fluid delivery device or system which either monitored or unmonitored, delivers a fluid, accurately and precisely, at a relatively constant adjustable and controlled rate over an industrially recognized extended period of time.
The present invention is directed to a fluid delivery device comprising: (a) a reaction chamber, wherein the reaction chamber is capable of containing a chemical reagent which expands upon a chemical reaction; (b) a membrane associated with the reaction chamber in a fixed position; (c) a displaceable member positioned between the reaction chamber and a reservoir, wherein the displaceable member is displaced upon expansion of the chemical reagent; and (d) a reservoir, wherein the reservoir is capable of containing a fluid which is delivered upon displacement of the displaceable member.
In a preferred embodiment of the present invention, the reaction chamber includes a chemical reagent which expands upon a chemical reaction, such as corrosion, oxidation, reduction, etc. In this embodiment, the chemical reagent may be selected from the group consisting of: metals and other chemical compounds, such as metals including Fe, Zn, Al, Ca, Mg, their alloys and compounds and mixtures thereof.
In another preferred embodiment of the present invention, the membrane is oxygen and moisture permeable and optionally includes a cover member which, upon its removal, allows oxygen and/or moisture into the reaction chamber.
In yet another preferred embodiment of the invention, the displaceable member may be selected from the group consisting of a piston, bladder, diaphragm, plunger, and combinations thereof.
In accordance with the present invention, the reservoir contains a fluid, such as a medicament, lubricant, surfactant, disinfectant, deodorant, pesticide, insecticide, herbicide, and mixtures thereof.
The present invention is further directed to a fluid delivery device comprising: (a) a reaction chamber which includes at least one of the following: metal, metal alloys, metal compounds, electrolyte solutions, hydrogen scavengers, or mixtures thereof, which expand upon a chemical or electrochemical reaction in combination with or without an osmotic process; (b) a membrane associated with the reaction chamber in a fixed position, wherein the membrane is hydrogen, oxygen and moisture permeable; (c) a displaceable member positioned between the reaction chamber and a reservoir, wherein the displaceable member is displaced as a result of the chemical or electrochemical reaction with the metal, metal alloys, metal compounds and electrolyte solutions or mixtures thereof, in combination with or without an osmotic process; and (d) a reservoir, wherein the reservoir is capable of containing a fluid which is delivered upon displacement of the displaceable member.
In a preferred embodiment of the invention, the reservoir includes one or more apertures.
The present invention is also directed to a fluid delivery device comprising: (a) a reaction chamber, wherein the reaction chamber includes at least one of a metal, metal alloy, metal compounds or combinations thereof, which expands upon chemical and/or eletrochemical reaction; (b) a membrane associated with the reaction chamber in a fixed position, wherein the membrane is hydrogen, oxygen and moisture permeable; (c) a displaceable member positioned between the reaction chamber and a reservoir, wherein the displaceable member is displaced upon expansion of the metal, metal alloy and/or metal compounds with an electrolyte and/or oxygen; and (d) a reservoir, wherein the reservoir contains a fluid which is delivered upon displacement of the displaceable member, the fluid being selected from the group consisting of a medicament, lubricant, surfactant, disinfectant, deodorant, pesticide, insecticide, herbicide, and mixtures thereof.
The present invention is further directed to a fluid delivery device comprising: (a) a first electrode having a first active material, wherein the first active material expands upon a chemical and/or electrochemical reaction; (b) a second electrode having a second active material; (c) a separator positioned between the first and second electrodes; (d) a membrane associated with the second electrode in a fixed position; (e) a displaceable member positioned between the first electrode and a reservoir, wherein the displaceable member is displaced upon expansion of the first active material; and (f) a reservoir, wherein the reservoir is capable of containing a fluid which is delivered upon displacement of the displaceable member.
In a preferred embodiment of the present invention, the first electrode comprises an anode which may be fabricated from metal, for example, Zn, Fe, Al, Ca, Mg, or mixtures thereof and the second electrode comprises, for example, a cathode which may comprise air, or an electrode, such as a carbon Teflon composite electrode which facilitates an oxidation reaction with the first electrode.
Preferably, a resistor is provided in electrical communication with the first electrode to controllably regulate discharge rate of the anode. Such discharge rates will be readily discernable from those having ordinary skill in the art, as exemplified in the publication entitled xe2x80x9cHandbook of Batteries, Second Editionxe2x80x9d at Chapter 13, xe2x80x9cZinc/Air Cells,xe2x80x9d Steven F. Bender, et al. (available from McGraw-Hill, Inc.).
The present invention is also directed to a fluid delivery device comprising: (a) a first electrode having a first active material, wherein the first active material expands upon a chemical and/or electrochemical reaction; (b) a second electrode having a second active material; (c) an electrolyte positioned between the first and second electrodes in a fixed position; (d) a displaceable member positioned between the first electrode and a reservoir, wherein the displaceable member is displaced upon expansion of the first active material; and (e) a reservoir, wherein the reservoir is capable of containing a fluid which is delivered upon displacement of the displaceable member.
In a preferred embodiment of the present invention, the first electrode comprises a cathode which may be fabricated from a metal halide, metal chalconide, such as PbI2, BiI3, PbS, Bi2S3, etc., the second electrode comprises an anode which may be fabricated from single valent metal, such as Li, Na, Cu, Ag, Au, etc., and the electrolyte comprises a rigid solid phase electrolyte fabricated from a lithium ion conductor, for example, LiIxe2x80x94Al2O3, lithium beta aluminum and a lithium conducting polymer electrolyte.